For devices such as a fan motor in an outdoor unit of an air-conditioning apparatus, the efficiency has been enhanced in response to a demand for energy saving, and AC motors have been increasingly replaced with brushless DC motors. The brushless DC motor employs a configuration in which, to avoid electrical corrosion of a bearing due to current caused at a shaft as an axis, a rotor core of a rotating motor is divided into inner and outer cores, and an elastic body is inserted into an annular clearance left between the inner and outer cores (for example, Patent Literature 1).
Circular ring-shaped iron core pieces forming the outer core in Patent Literature 1 are formed by continuously punching out the iron core pieces from a band-shaped steel sheet material, leading to a poor material yield rate. For this reason, for a core structure of the rotating motor, a method has been also employed in which concave and convex portions provided at end surfaces of adjacent ones of a plurality of fan-shaped divided cores in the circumferential direction of the divided cores are fitted together, and then, an annular rotor iron core is integrally formed using an elastic body (for example, Patent Literature 2).